Daredevil Felix Baumgartner of Austria trained for days during two visits to the altitude chamber at San Antonio's Brooks City Base in preparation for his world record-setting jump from a balloon nearly 24 miles above the Earth.

An altitude chamber at San Antonio's Brooks City-Base used decades ago in development of the U.S. space program played a key role in Felix Baumgartner's record-breaking skydive over New Mexico on Sunday.

To prepare for his televised leap from more than 24 miles up, Baumgartner and his capsule were tested in a large environmental chamber at Building 160 at Brooks, part of an aerospace complex dedicated by President John F. Kennedy. Although hypoxia, or lack of oxygen, was a key concern, Baumgartner was surprised how cold it felt, even while wearing his protective suit, when the temperature in the chamber was lowered to -50 degrees Fahrenheit.

"I remember hearing him say, 'It's pretty cold' - a lot colder than he expected," said Bill Ercoline, manager of San Antonio operations for Wyle, an aerospace firm and tenant at Brooks.

Broke sound barrier

During a weeklong visit in November 2011, Baumgartner and his capsule "went up" on three simulations in the chamber, including one at an altitude of 120,000 feet - the highest level ever replicated in the facility, Ercoline said. When the 43-year-old skydiver stepped off the pod, the chamber simulated a rapid descent.

The specially designed capsule built by Sage Cheshire Aerospace for the Red Bull Stratos project was returned to Brooks for more tests in the chamber on Sept. 24.

"They wanted to make sure everything worked correctly. And they wanted to keep him safe," Ercoline said.

John "Mac" McCarthy, director of facilities and infrastructure with the Brooks Development Authority, said he and his wife and friends intently watched the jump Sunday on the Discovery Channel. Baumgartner set a record for the highest human freefall and was the first skydiver to break the speed of sound, reaching a peak velocity of 833.9 mph.

"It was pretty intense," McCarthy said. "This furthered our knowledge of how a human can survive these various elements."

Aid to astronauts

McCarthy said the successful jump serves as a testament that the equipment used for years by astronauts and jet pilots can still save lives.

Brooks was run by the military from 1917 to 2011, but no longer is an Air Force base. The development authority owns the buildings and equipment, and is converting the base to a planned, mixed-use community.

"Even though it has some age on it, it still is cutting-edge equipment," McCarthy said.

Ercoline said the altitude chamber has been used to test consumer products. One test, aimed at simulating a rapid descent of a commercial airliner, gauged the effects of altitude change on a laptop computer.

"We do a wide range of experiments with these chambers," Ercoline said.